Hydro-pneumatic spring system, especially for motor vehicles

ABSTRACT

A shock absorbing and automatic level control operating cylinder with a hollow piston rod reciprocable therein and having a highpressure storage and an operating chamber. A hollow pump rod is axially movable in said hollow piston and a pump piston is carried by a free end of the hollow pump rod. A valve body is slidably guided with respect to the pump rod and has an abutment engageable upon the pump piston. An insert member has a surface liftable with respect to a valve seat provided by the valve body and a throttle-forming bore means makes possible passage of hydraulic medium from the high-pressure storage into the operating chamber. A preloaded tension spring means presses upon a surface of the insert member for interrupting pump operation. Additional check valves are provided for opening of high-pressure storage and for making possible pump operation.

United States Patent 2/ I 970 Tulzek...

Primary Examiner.lamcs B. Marbert Atwrney walter Becker [72] InventorManiredLohr ABSTRACT: A shock absorbing and automatic level controloperating cylinder with a hollow piston rod reciprocable therein andhaving a high-pressure storage and an operating chamber. A hollow p umprod is axially movable in said hollow piston and a pump piston iscarried by a free end of the hollow ESPECIALLY FOR MOTOR VEHICLES 16Claims, 5 Drawing Figs.

\ pump rod. A valve body is slidably guided with respect to the pump rodand has an abutment engageable upon the pump U-S- piston. Ah insertmember has a surface liftable with respect to Ink a valve seat providedby the valve body and a throttle-forming 501 FieldofSearch..................w.r

bore means makes possible passage of hydraulic medium from 8 thehigh-pressure storage into the operating chamber. A preloaded tensionspring means presses upon a surface of the in- [56] References CitedUNITED STATES PATENTS 11/1967 Axthammeretal.........

PATENTFU JUL 20 Ian SHEET 1 BF 5 PATENTED JUL 20 lSil SHIIH u nr 5 FIG.4

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ATENIH] JUL 2 0 Ian SHEET 5 0F 5 HYDRO-PNEUMATIC SPRING SYSTEM,ESPECIALLY FOR MOTOR VEHICLES The present invention relates to ahydropneumatic spring system with hydraulic damping effect or if desiredwithout a damping effect, and with automatic level control, which springsystem will be able to control or stabilize the loads during astandstill and the relief during the drive, especially for motorvehicles, said spring system comprising two separate preloaded gascushions operable to act upon a hydraulic medium which, by means ofapumping or control mechanism arranged in a hollow piston rod, iscontrolled in conformity with the load.

Hydropneumatic spring systems or elements are known by means of whichthe nominal level of the vehicle is obtained under load only after thevehicle has driven a certain distance, and by means of which whenrelieved of load the'standing vehicle is brought back to its nominallevel. Spring elements or systems of this type have the drawback thatwhen installed on the rear axle, after the vehicle has been loaded, theposition of the bright lights will not be correct as long as the vehicleis below the nominal level whereby during night driving the driver ofthe oncoming vehicle will be blinded. Moreover, with a fully loadedvehicle, the residual travel stroke of the spring is relatively short.

When combining such hydropneumatic spring element with a steel spring,the fully loaded vehicle will at the start of its travelling move alonga too soft spring line of characteristic. When driving through a curveor cornering this leads to a transverse tilting of the vehicle.

There has also become known a hydropneumatic spring element which whenthe vehicle is at a standstill levels or regulates upwardly and when thevehicle is being driven levels out a previously effected relief, which,however, has the drawback that the pumping effect is speed responsiveand has no socalled normal range whereby after reaching its level, thepump will not be turned offso that the vehicle carries out a continu'ous upward and downward movement or plays around the nominal level.

Another heretofore known design of the type involved lacks a dampingsystem and practically cannot be realized inasmuch as the spring of thepushrod valve cannot produce the necessary high forces at correspondingspring strokes which are required for the opening of the check valve ofthe high pressure accumulator when the vehicle is empty.

It is, therefore, an object of the present invention to provide ahydropneumatic spring system which will make it possible that when thestanding vehicle is under load the desired level will be reachedimmediately and when the vehicle is relieved after having driven over acertain distance, the desired level will be reached.

It is another object of this invention to provide a hydropneumaticspring system or spring arrangement as set forth in the precedingparagraph which for avoiding continuous upward leveling and pumpingoperations will have a normal range.

These and other objects and advantages of the invention will appear moreclearly from the following specification, in connection with theaccompanying drawings, in which:

FIG. 1 shows a hydropneumatic spring system according to the inventionin the pumping range.

FIG. 2 shows the hydropneumatic spring system according to the inventionin its normal range.

FIG. 3 illustrates the hydropneumatic spring system according to theinvention in its upward-leveled range.

FIG. 4 represents a hydropneumatic spring element according to theinvention with a high pressure accumulator above the upper suspension.

FIG. 5 is a hydropneumatic spring system without damping in its normalrange.

The hydropneumatic springsystem according to the present invention ischaracterized primarily in that in the interior ofa hollow piston rodthere is axially movably arranged a hollow pump rod the nonclamped-inend of which is provided with a pump piston having axially movably andslidably mounted thereon a valve bodywhich in its upward leveling orupward regulating range hasiits abutment engage the pump piston wherebythe valve seat of said valve body is lifted off from a surface of aninsert member and through the intervention of a throttle bore, thepassage of hydraulic "fluid from a high-pressure accumulator to aworking chamber is made possible. When the piston rod moves into thisposition, the abutment closes the check valve in the pump piston wherebyouter influences upon the spring line of characteristic are limited to aminimum. Within the normal range, the valve body is adapted by means ofthe pressure in the high-pressure accumulator which pressure actsthrough bores and an annular passage of the pump piston, a longitudinalgroove of the valve body and the bores of the abutment upon the valveseat, is pressed upon the surface of the insert member in a sealingmanner whereby the pumping effect will be interrupted whereas within thepumping range the valve body operates as suction valve and incooperation with the check valve in the pump piston makes possible apumping effect.

By means of a damping piston, a damping effect will be realized which isindependent of the respective load or working position of the springsystem. This damping effect will in the pulling direction be bufferedbetween fixed walls, whereasthe pressure direction is determined by thepressure of the working chamber and is by means of a valve arranged inthe guiding means for the rod limited in such a way that below thedamping piston no low pressure will occur.

When installation space is lacking, a particularly advantageous designof the hydropneumatic spring system according to the invention isrealized by arranging the high-pressure accumulator for instance in thetrunk of the vehicle, said highpressure accumulator being screwed ontoan upper suspension system formed by a pin suspension. By means of twocheck valves which are opened only when screwing on the high-pressureaccumulator, the spring element or spring system and the high-pressureaccumulator can be filled separately and can be subjected to acorresponding pressure. By means of a pipe of synthetic material, e.g.polyvinylchloride, which pipe may have its upper end designed forinstance as a sealing ring, gas and hydraulic liquid are separated fromeach other in the spring system.

A very simple hydropneumatic spring system without damping is obtainedwhen during the compression of the spring (Einfedem) hydraulic liquidis, by a check valve in the piston, drawn into the space between thepiston and the piston rod, which liquid when the piston and piston rodmove outwardly is, by lifting off the valve body, pumped into thehigh-pressure accumulator until the piston ring of the piston moves overa longitudinal groove in the cylinder and thus ends the pumping effect.

Referring now to the drawings in detail, a hydropneumatic spring elementor spring system inthe pump range of FIG. 1 is,

' by means of an upper suspension ll, connected to the vehicle body and,by means of a lower suspension 2, is connected to the axle of thevehicle. An outer mantle 3 which at one endis closed by a bottom 4encloses the hydropneumatic spring system. The bottom 4 is provided witha piston rod seal 5 while a further seal 6 is interposed between thebottom 4 and the outer mantle or jacket 3. A hollow piston rod 7 isadapted to slide in guiding means 8 and is provided with an insertmember 9 carrying a damping piston 10 movable in a cylinder 11. Anannular chamber I6 is formed by a supporting pipe 12 with openings 13 atthe lower end thereof, and by the cylinder 11 with openings 14 at theupper end of said cylinder Ill, said.

upper end resting against a supporting body 15.

A working chamber 17 between an intermediate member 18 and the bottom 4is subdivided into a working gas chamber 17I and a working fluid chamber172. The said intermediate member 18 separates the working chamber 17from a high pressure accumulator 19 which in its turn is subdivided byan elastic separating member 20 into a high-pressure gas chamber 191 anda high-pressure fluid chamber 192. The supporting body is provided withpassages 21 and furthermore comprises a pump limiting valve 22 and anelastic suspension 23 of a hollow pump rod 24 the hollow end of whichcarries a pump piston 25. Piston 25 is provided with piston rings 26 and27 which are so arranged that an annular passage 28 is formedthcrebetween which passage through bores 29 communicates with an innerbore 30 of the hollow pump rod 24 and also comprises a check valve 31.The pump piston 25 is slidably guided in a valve body 32 which in itsupper end has a valve seat 33 a throttling bore 34 while its lower endis provided with a longitudinal groove 35, an abutment 36, and a closuremember 37. The valve body 32 is pressed by a preloaded tension spring 38against a surface 40 of the insert member 9. The spring 38 is connectedfor instance to the closure member 37 and is furthermore for instance bya ring 39 connected to the hollow piston rod 7.

When the piston rod 7 moves outwardly, the check valve 31 closes, andhydraulic fluid passes from the working liquid chamber 172 throughopenings 13, annular chamber 16, and openings 14 into a chamber 41 abovethe damping piston 10. Furthermore, a portion of the hydraulic liquid ina quantity corresponding to the pump rod cross section passes through adamping bore 42, a connecting bore 43, an annular passage 44, and a bore45, by the valve body 32 being lifted, into the chamber 46 of the hollowpiston rod 7v Simultaneously, hydraulic liquid is pressed from a chamber47 below the damping piston 10 through a pull-direction damping valve 48(Zugstufendampfungsventil) into the chamber 4. whereby thepull-direction damping is realized.

When the piston rod 7 moves inwardly, the valve body 32 will, by meansof the valve seat 33, sealingly engage the surface 40 of the insertmember 9, and the hydraulic liquid drawn in during the pulling stage is,by opening the check valve 31, pressed from the chamber 46 through theinner bore 30 of the hollow pump rod 24 and the passages 21 into thehigh-pressure liquid chamber 192. Simultaneously,hydraulic fluid flowsfrom chamber 41 through a pressure stage damping valve 49 into thechamber 47 thereby realizing the pressure stage damping. in view of thispumping operation, the pressure effective for the supporting force ofthe spring system is reduced in the working chamber 17 whereby thehollow piston rod 7 moves inwardly until the level of the vehicle hasbeen reached. For safety reasons, the pump-limiting valve 22 is arrangedin the supporting body 15. This valve 22 will prevent the pres sure inthe high-pressure accumulator from increasing unduly to a nonpermissibleextent, especially when'thc spring system is rigidly clamped in, forinstance, for testing purposes.

in the normal range (P16. 2) of the spring system, the chamber 46 willbe under the pressure of the high-pressure accumulator 19 through thepassages 21, the inner bore 30 of the hollow piston, rod 20, the bores29, annular passage 28, longitudinal groove 35, and openings 50 in theabutments 36. [n this way, the valve seat 33 of the valve body 32 ispressed sealingly against the surface 40 whereby the pump effect isinterrupted. Within this normal range, when moving the piston rod 7,hydraulic fluid is, in conformity with the cross section 'of the hollowpump rod 24, movedback and forth between the chamber 46 and the highpressure fluid chamber 192. The

damping is effected in the same manner as described above in connectionwith Figure 1.

For limiting the pressure stage damping and for purposes of preventingunderpressure conditions in chamber 47, a pressure stage limiting valve51 is provided which opens when a and connecting bores 53. ln order toassure that the vehicle under its respective load will also staticallymaintain its normal position, the insert member 9 is provided with aseal 54 which prevents the escape of hydraulic fluid from thehigh-pressure liquid chamber 192 through chamber 46 into chamber 41 andback to the working fluid chamber 172. In upward leveling 7 position(Aufregelstellung)FlG. 3-, the abutment 36 will,

when the hollow piston rod 7 is moved inwardly, engage the pump piston25, and the valve seat 33 on valve body 32 is lifted off from thesurface 40 of the insert member 9 so that hydraulic liquid will from thehigh-pressure liquid chamber 192 pass through openings 21, inner bore30, bores 29, annular passage 28, longitudinal groove 35, throughthrottling bore 34, into the chamber 46, and from there will passthrough bore 45, annular passage 44, connecting bore 43, and dampingbore 42, into the chamber 41 and from here through openings 14, annularchamber 16, and openings 13 into the working fluid chamber 172. in thisway the pressure in the working chamber 17 increases, and the piston rod7 moves outwardly until the surface 40 of the insert member 9 againseats onto the valve seat 33 whereby the level of the vehicle has beenreached again. When the vehicle swings through, by closing the checkvalve 31, the now covered bores 50in the abutment 36 prevent hydraulicliquid from passing from chamber 41 through chamber 46 into thehigh-pressure liquid chamber 192. Also, in this position, the damping isobtained which has been described in connection with FIG. 1. I

Figure 4 represents a modification of the spring system according to theinvention according to which a high-pressure accumulator 55 is arrangedabove an upper'suspension 56. The outer diameter of the spring elementor spring system is with this design considerably reduced when lack ofinstallation space exists. Advantageously, the upper suspension 56 formsa so-called pin suspension into which is built in a check valve 57.After screwing on the high-pressure accumulator 55 and sealing the sametoward the outside by a seal 58, first the check valve 57 and afterfurther tightening a check valve 59 of the high-pressure accumulator 55is opened, and the connection between the high-pressure liquid pressure552 and a chamber 60 is freed. A working chamber 61 is in this instanceadvantageously by means of a pipe 62 of synthetic material having itsupper end forming a sealing ring 63 and having its lower end immersed inthe slight liquid level of the working chamber 61, subdivided into aworking gas chamber 611 and a working fluid chamber 612. This iseffected in such a way that when the hollow piston rod 7 is in motion,only hydraulic fluid can pass from the working fluid chamber 612 throughan annular chamber 64 and via openings 14 into the chamber 41.

A hydropneumatic spring element or spring system without damping isillustrated in FIG. 5. Within the pumping range, when the hollow pistonrod 65 moves'inwardly, a check valve 66 is lifted off by a piston 67 andfills a'chamber 68 below the piston 67 with hydraulic fluid from achamber 69 above the piston 67, which chamber 69 communicates throughopenings 17, annular chamber 71 and openings 72 with the working fluidchamber 732. a

When the piston rod 65 moves outwardly, by closing the check valve 66and lifting a valve seat 86 of a valve body 74 off a surface 75 of thepiston 67, the previously drawn-in liquid is from the chamber 68 pressedthrough a channel 76 into a chamber 77 and from there through bores 78,79, and 80 ofa connecting rod 81 into a high-pressure liquid chamber822. The piston rod 65 moves inwardly until a piston ring 83 passes overa groove 84 in a cylinder 85 whereby the pump effect is ended. In thisnormal position, the pressure of a highpressure accumulator 82 actsthrough bores 80, 79, 78 onto the valve seat 86 of the valve body 74 andpresses the same together by means of the preload of a pull spring 87 ina sealing manner against the surface 75 of piston 77. When the vehicleis loaded and thepiston 65 moves inwardly, an abutment 88 of the valvebody 74' engages the bores 79 of a closure member 89 whereby the valveseat 86 with the valve body 74 is lifted off the surface 75 andhydraulic liquid is passed from the high-pressure liquid 822 through abore 80, and a throttling bore 90 into the chamber 77 and from therepasses through passage 76 into the chamber 68 and through groove 84 intothe chamber 69. From here the liquid passes through openings 70 into theannular chamber 71 and openings 72 in the working fluid chamber 732whereby an increase in the working gas chamber 731 will be realizedwhich bririgs about an-outwardly movement of the piston rod 65 until thevalve seat 86 again seats on the surface 75 and the vehicle is again onthe desired level. In order to be able to keep the vehicle also whilehis standing still over a longer period of time at the desired level, aseal 91 is provided. h

it is, of course, to be understood that the present invention is, by nomeans, limited to the specific showing in the drawings, but alsocomprises modifications within the scope of the appended claims.

What I claim is;

ll Ahydropneumatic spring system having automatic level control both forregulation of loads during standstill and relief thereof controlledduring running operation, especially for motor vehicles with twoseparate preloaded gaseous cushions operable toact upon a hydraulicmedium which is controlled according to loadby a purhp and controlmechanism, which compr ses: a cylinder, a hollow piston rod rcciprocablyarranged in said cylinder, a high pressure fluid storage container,operating chamber means associate with said cylinder, a hollow pump rodhaving an axial bore and being axially movable in said hollow pistonrod, a pump piston carried by a free end of said hollow pump rod, atvalve body slidablyguided with respect to said hollow pump rod andhaving an abuttneht operable in upward leveling position to test againstsaid pump piston, said valve body includihg valve seat means, an insertmember having a seat surface adapted to be engaged and disengaged bysaid valve seat means, and throttle means associated with said valvebody and operable in response to said valve seat means disengaging saidseat surface to estttblishfluid communication between said high-pressurefluid storage container and said operating chamber.

L A hydropneumatic spring system according to claim 1, which inclu des acheck valve arranged in said pump piston, and in which in upwardleveling position said abutment is operable to cover said check valve soas to rearwardly seal and close thc same,

3. A hydropneumatic spring system having automatic level control forregulation of loads during standstill and relief thereof during runningoperation, especially for inotorvchicles with two separate preloadedgaseous cushions operable to act upon a hydraulic medium which iscontrolled accbrding'to load by a pump and control mechanism, whichcomprises: a cyliilder, a hollow piston rod reciproeably arranged insaid cylinder, a high-pressure fluid storage container, operatingchamber means associated with said cylinder, a hollow pump rod having anaxial bore and being axially movable in said hol low piston rod, a pumppiston carried bya free end of said hollow ptlnip rod, a valve bodyslidably guided with respect to said hollow purnp rod and having anabutment operable in upward leveling position to rest against said umppiston, said valve body including valve seat means, an insert memberhaving a seat surface adapted to be engaged and disengaged by said valveseat means, throttle means associated with said valve body and operablein response to said yalve seat means disengaging said seat surface toestablish fluid communication between said high-pressure fluid storagecontainer and said operating chamber, said pump piston being providedwith radial passage means and with an annular passage communicating withsaid radial passage means, and said valve body having longitudinalgroove means adapted in the normal range of said valve body tocommunicate with said annular passage for conveying the pressureprevailing in said high-pressure fluid storage container through saidradial passage means and said ahnular passage to said valve seat meansto press the same against said seat surface of said insert member, andpreloaded spring means continuously urging said valve seat means againstthe seat surface of said insert member.

4, A hydropneumatic spring system according to claim 3, in which inpumping range said valve body with the valve seat operating as the inletvalve arid making possible pump operation with said check valve iri saidpump piston.

5. A hydropneumatic spring system according to claim 3, ih which adamping piston is so provided inside said spring system that the suctionstepwise damping is buffered between rigid walls and the pressurestepwise damping is effected by means ofthe pressure in the operatingchamber. 3

6. A hydropneumatic spring system according to claim 3, which includesguiding means for said piston rod and also includes a pressure stepwiselimiting vaIli/e associated with said guiding means for opcrativelylimiting the pressure stepwise damping.

7. A hydropneumatic spring system according to claim 3, in which anoverpressure valve means is provided in a supporting body.

8. A hydropneumatlc spring system according to claim 3, which includesan upper suspension for said spring system and also includeshigh-pressure storage means arranged above said upper suspension.

9. A hydropneumatic spring system according to claim 8, in which aseparating clement formed at its upper end as a sealing ring is immersedin the slight liquid level of the operating chamber.

it). A hydropjncumatilc spring system having automatic level control forregulation of loads during standstill and relief thereof during runningoperation, especially for motor vchicles with two separate preloadedgaseous cushions operable to act upon a hydraulic medium whichiscontrolled according to load by a pump and control mechanism, whichcomprises: a cylinder, a hollow piston rod reciprocably arranged in saidcylinder, at high-pressure fluid storage container, operating chambermeans associated with said cylinder, a hollow pump rod having an axialbore and beihg axially movable in said hollow piston rod, :1 pump pistoncarried by a free end of said hollow pump rod, a valve body slldablyguided with ,respcctto said hollow pump rod and having an abutmentoperable in upward leveling position to rest against said pump piston,said valve body including valve seat meahs, an insert member having aseat surface adapted to be engaged and disengaged by said valve seatmeans, throttle means associated with said valve body and operable inresponse to said valve seat means discngaging said seat surface toestablish fluid communication between said high-pressure fluid storagecontainer and said operating chamber, an upper suspension for saidspring system and also high-pressure storage means arranged above saidupper suspension, and a check valve being provided in said uppersuspension. h i

ll. A hydropneumatic spring system according to clairn,l0 in which acheelt valve is installed in the high-pressure storage.

12. A hydropheumatic spring system according to claim 10, in whichduring installation of the high-pressure storage the'rb is an outwardsealing with respect thereto, a check valve being provided in said uppersuspension of 'the spring system and upon further tightened installationthere is opening of tho high-pressure storage by check valve means.

13. A hydropneumatic spring system having automatic level control forregulation of loads during standstill and relief thereof during runningoperation, especially for motor vehicles with two separatcpreloadedgaseous cushions operable to act upon a hydraulic medium which iscontrolled according to load by a pump and control mechanism, whichcomprises: a cylinder, a hollow piston rod reciprobably arranged in saidcylinder, a high-pressure fluid storage container, operating chambermeans associated with said cylinder, a hollow pump rod having an axialbore and being axially movable in said hollow piston rod, a pump pistoncarried by a free end of said hollow pump rod, a valve body slidablyguided with respect tb said hollow pump rod and having an abutmentoperable in upward leveling position to test against said pump piston,said valve body including valve seat means, an insert member having aseat surface adapted to be engaged and disengaged by said valve seat,mcans, throttle means associated with said valve body and operable inresponse to said valve seat means disengaging said seat surface toestablish fluid communication between said high pressure flu d storagecontainer and said operating chamber, particularly without hydraulicdamping there being provided ahollow connectingrod axially movableinternally of said hollow piston rod, a closure member pro- '15. Ahydropneumatic spring system according to claim 13, in which a pistonring in a groove in normal range controls upwardly in said operatingcylinder and thereby stops pump operation, while the pressure of thehigh-pressure storage through bores is operative upon a valve seat of avalve body and presses the same upon the surface of said piston andavoids a further upward regulation.

16' A hydropneumatic spring system according to claim 15, in which inpumping range the piston is located below the groove in said operatingcylinder, said check valve serving as a suction vent and said valve bodywith the pressure seat serving as a pressure vent whereby the pumpoperation is attained.

1. A hydropneumatic spring system having automatic level control bothfor regulation of loads during standstill and relief thereof controlledduring running operation, especially for motor vehicles with twoseparate preloaded gaseous cushions operable to act upon a hydraulicmedium which is controlled according to load by a pump and controlmechanism, which comprises: a cylinder, a hollow piston rod reciprocablyarranged in said cylinder, a high pressure fluid storage container,operating chamber means associated with said cylinder, a hollow pump rodhaving an axial bore and being axially movable in said hollow pistonrod, a pump piston carried by a free end of said hollow pump rod, avalve body slidably guided with respect to said hollow pump rod andhaving an abutment operable in upward leveling position to rest againstsaid pump piston, said valve body including valve seat means, an insertmember having a seat surface adapted to be engaged and disengaged bysaid valve seat means, and throttle means associated with said valvebody and operable in response to said valve seat means disengaging saidseat surface to establish fluid communication between said high-pressurefluid storage container and said operating chamber.
 2. A hydropneumaticspring system according to claim 1, which includes a check valvearranged in said pump piston, and in which in upward leveling positionsaid abutment is operable to cover said check valve so as to rearwardlyseal and close the same.
 3. A hydropneumatic spring system havingautomatic level control for regulation of loads during standstill andrelief thereof during running operation, especially for motor vehicleswith two separate preloaded gaseous cushions operable to act upon ahydraulic medium which is controlled according to load by a pump andcontrol mechanism, which comprises: a cylinder, a hollow piston rodreciprocably arranged in said cylinder, a high-pressure fluid storagecontainer, operating chamber means associated with said cylinder, ahollow pump rod having an axial bore and being axially movable in saidhollow piston rod, a pump piston carried by a free end of said hollowpump rod, a valve body slidably guided with respect to said hollow pumprod and having an abutment operable in upward leveling position to restagainst said pump piston, said valve body including valve seat means, aninsert member having a seat surface adapted to be engaged and disengagedby said valve seat means, throttle means associated with said valve bodyand operable in response to said valve seat means disengaging said seatsurface to establish fluid communication between said high-pressurefluid storage container and said operating chamber, said pump pistonbeing provided with radial passage means and with an annular passagecommunicating with said radial passage means, and said valve body havinglongitudinal groove means adapted in the normal range of said valve bodyto communicate with said annular passage for conveying the pressureprevailing in said high-pressure fluid storage container through saidradial passage means and said annular passage to said valve seat meansto press the same against said seat surface of said insert member, andpreloaded spring means continuously urging said valve seat means againstthe seat surface of said insert member.
 4. A hydropneumatic springsystem according to claim 3, in which in pumping range said valve bodywith the valve seat operating as the inlet valve and making possiblepump operation with said check valve in said pump piston.
 5. Ahydropneumatic spring system according to claim 3, in which a dampingpiston is so provided inside said spring system that the suctionstepwise damping is buffered between rigid walls and the pressurestepwise damping is effected by means of the pressure in the operatingchamber.
 6. A hydropneumatic spring system according to claim 3, whichincludes guiding means for said piston rod and also includes a pressurestepwise limiting valve associated with said guiding means foroperatively limiting the pressure stepwise damping.
 7. A hydropneumaticspring system according to claim 3, in which an overpressure valve meansis provided in a supporting body.
 8. A hydropneumatic spring systemaccording to claim 3, which includes an upper suspension for said springsystem and also includes high-pressure storage means arranged above saidupper suspension.
 9. A hydropneumatic spring system according to claim8, in which a separating element formed at its upper end as a sealingring is immersed in the slight liquid level of the operating chamber.10. A hydropneumatic spring system having automatic level control forregulation of loads during standstill and relief thereof during runningoperation, especially for motor vehicles with two separate preloadedgaseous cushions operable to act upon a hydraulic medium which iscontrolled according to load by a pump and control mechanism, whichcomprises: a cylinder, a hollow piston rod reciprocably arranged in saidcylinder, a high-pressure fluid storage container, operating chambermeans associated with said cylinder, a hollow pump rod having an axialbore and being axially movable in said hollow piston rod, a pump pistoncarried by a free end of said hollow pump rod, a valve body slidablyguided with respect to said hollow pump rod and having an abutmentoperable in upward leveling position to rest against said pump piston,said valve body including valve seat means, an insert member having aseat surface adapted to be engaged and disengaged by said valve seatmeans, throttle means associated with said valve body and operable inresponse to said valve seat means disengaging said seat surface toestablish fluid communication between said high-pressure fluid storagecontainer and said operating chamber, an upper suspension for saidspring system and also high-pressure storage means arranged above saidupper suspension, and a check valve being provided in said uppersuspension.
 11. A hydropneumatic spring system according to claim 10, inwhich a check valve is installed in the high-pressure storage.
 12. Ahydropneumatic spring system according to claim 10, in which duringinstallation of the high-pressure storage there is an outward sealingwith respect thereto, a check valve being provided in said uppersuspension of the spring system and upon further tightened installationthere is opening of the high-pressure storage by check valve means. 13.A hydropneumatic spring system having automatic level control forregulation of loads during standstill and relief thereof during runningoperation, especially for motor vehicles with two separate preloadedgaseous cushions operable to act upon a hydraulic medium which iscontrolled according to load by a pump and control mechanism, whichcomprises: a cylinder, a hollow piston rod reciprocably arranged in saidcylinder, a high-pressure fluid storage container, operating chambermeans associated with said cylinder, a hollow pump rod having an axialbore and being axially movable in said hollow piston rod, a pump pistoncarried by a free end of said hollow pump rod, a valve body slidablyguided with respect to said hollow pump rod and having an abutmentoperable in upward leveling position to rest against said pump piston,said valve body including valve seat means, an insert member having aseat surface adapted to be engaged and disengaged by said valve seatmeans, throttle means associated with said valve body and operable inresponse to said valve seat means disengaging said seat surface toestablish fluid communication between said high pressure fluid storagecontainer and said operating chamber, particularly without hydraulicdamping there being provided a hollow connecting rod axially movableinternally of said hollow piston rod, a closure member provided in theunpreloaded end of said connecting rod, a valve body portion likewiseaxially movable to slide upon said closure member and engageable inregulating range to abut upon said closure member, said valve bodyportion thereby lifting from a valve seat of a surface of a piston andmaking possible passage of hydraulic medium from the high pressurestorage into an operating chamber through a throttle bore in saidclosure member.
 14. A hydropneumatic spring system according to claim13, in which in the regulation position said abutment uncovers sealingof said bores.
 15. A hydropneumatic spring system according to claim 13,in which a piston ring in a groove in normal range controls upwardly insaid operating cylinder and thereby stops pump operation, while thepressure of the high-pressure storage through bores is operative upon avalve seat of a valve body and presses the same upon the surface of saidpiston and avoids a further upward regulation.
 16. A hydropneumaticspring system according to claim 15, in which in pumping range thepiston is located below the groove in said operating cylinder, saidcheck valve serving as a suction vent and said valve body with thepressure seat serving as a pressure vent whereby the pump operation isattained.